1. The process by which energy is propagated through space or matter. 2. The emission of rays in all directions from a common center. 3. Ionizing rays used for diagnostic or therapeutic purposes. Two types of radiation therapy are commonly used for patients with cancer: teletherapy and brachytherapy. SEE: brachytherapy4. Any form of radiant energy emission or divergence, as of energy in all directions from luminous bodies, radiographical tubes, particle accelerators, radioactive elements, and fluorescent substances. 5. In neurology, a group of fibers that diverge from a common origin.

1. The process by which energy is propagated through space or matter. 2. The emission of rays in all directions from a common center. 3. Ionizing rays used for diagnostic or therapeutic purposes. Two types of radiation therapy are commonly used for patients with cancer: teletherapy and brachytherapy. SEE: brachytherapy4. Any form of radiant energy emission or divergence, as of energy in all directions from luminous bodies, radiographical tubes, particle accelerators, radioactive elements, and fluorescent substances. 5. In neurology, a group of fibers that diverge from a common origin.

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